When a product is ready to be made there are specific types of documentation that manufactures need so that they can make the product. These documents are typical 2D Drawings and 3D CAD files. These documents are used to communicate all the information required by the manufacturer so that they can make the product. These documents are a legal document and should be treated as such. If there is ever a discrepancy between what a manufacture delivers, and what a client wanted the handoff documentation is consulted to determine fault.
Individual part design is a foundational skill for product designers or design engineers. The best part designs are simultaneously driven by form and function. Manufacturing constraints, performance requirements and product life cycles are also woven into the process. 3D CAD modeling software is the primary tool used to develop parts